The application relates to the field of intervertebral cages and generally to the field of implants intended to be implanted between two adjacent vertebrae to at least partly supplant an intervertebral disc and more particularly, to expansible vertebral implants of the intersomatic cage type.
To remedy to certain pathologies, sometimes it is sought to obtain the fusion of at least two vertebrae, for example when at least one of their adjacent intervertebral discs is lesioned.
From the state of the art, diverse arthrodesis techniques are known, based on diverse types of implants, such as for example intersomatic cages inserted into the place of a disc to promote bone growth arthrodesis and to secure between them two vertebrae.
Such devices are for example illustrated in patent application FR1651637 filed in February 2016, which has intersomatic cages giving the possibility of supplanting an intervertebral disc.
Further, to maximize and enhance the stability and the graft volume contained in such implants, the latter have to cover a volume which approaches as close as possible to the volume occupied by the lesioned vertebral disc. The implants of the prior art therefore generally have a very large volume making their implantation rather invasive for the patient.
A solution, used for reducing the size of the implants during their implantation, was the use of expansible cages such as those described for example in document EP1699389. Such cages, once they are implanted, are deployed by the surgeon to cover a volume approaching the volume of an intervertebral disc and to have a profile giving the possibility of tracking the lordosis of the vertebral column, thereby improving comfort for the patient and stability of the cage.
Nevertheless, this type of expansible cages has a certain number of drawbacks. In particular, during their expansion, the surgeon should exert inordinate pressure on the implant given that its expansion is simultaneously ensured on two axes orthogonal with each other. Further, it is more difficult for the surgeon to observe a specific lordosis. Finally, this type of implant does not rest or only very little on the cortical bone of the vertebra, but on a softer portion of the bone, which reduces its stability and has a risk of sinking therein.